The subject matter of the present invention relates to a novel apparatus and method for assembling uphole a plurality of wellbore apparatus of any desired length prior to disposing the plurality of wellbore apparatus downhole in a wellbore. More particularly, the subject matter of the present invention relates to a method and apparatus for perforating long length intervals of a wellbore during a single run into the wellbore by assembling uphole a tool string of any desired length prior to lowering the tool string into a pressurized wellbore, the tool string including a plurality of perforating apparatus interleaved with a corresponding plurality of snaplock connectors.
Typically, when perforating long length intervals of oil and gas wells that have sufficient reservoir pressure to create a surface pressure, the owner of the wellbore had three options: (1) kill the well, pull the perforating guns out of the wellbore, and then run completion equipment back into the wellbore, (2) drill a rathole below the formation to be perforated, the length of the rathole being at least as long as the length of the formation to be perforated, so that the perforating guns can be dropped off after perforating, the perforating guns falling to the bottom of the rathole, and (3) run small perforating guns through the completion equipment. None of the above options provide optimal solutions to perforating such a wellbore. Another limiting factor relates to the length of the pressure equipment (lubricator) that can physically fit within a structure, such as a drilling or workover rig. In that case, if the intent is to perforate a long length interval of the formation underbalanced, it was necessary to shoot a short length interval of the formation underbalanced, the short length being dictated by the limited length of the lubricator, and then to shoot a plurality of additional short length intervals of the formation during a corresponding plurality of additional runs of the short perforating guns into the wellbore. This results in a less than optimum perforating technique and well performance.
The steps of killing the well, pulling the perforating guns out of the well, and rerunning the completion equipment back into the wellbore can result in damage to the formation to such an extent that the well may never produce as well as it did immediately after perforating. Furthermore, drilling a rathole that is at least as long in length as the perforated interval is very expensive, often resulting in costs of as much as $500,000. Running small perforating guns through the completion equipment results in shallow, small diameter perforation holes that may limit production from the well or the completion equipment.